1. Field of the Invention
The present invention relates to straddle-type vehicles, and more particularly, to the location of the engine control unit and ignition coil.
2. Description of the Related Art
Straddle-type vehicles include motorcycles, for example. Motorcycles are disclosed in JP 2012-56441 A and JP 2010-167796 A, for example.
According to JP 2012-56441 A, a motorcycle includes a body frame. The body frame includes a head pipe, main frame, center frame, down frame and lower frame. The body frame supports the engine. A fuel tank is located above the engine. The fuel tank is supported by the main frame. A seat is located rearward of the fuel tank. The seat is supported by the seat frame. The seat frame extends rearward from the top end of the center frame. A rear frame is located rearward of the seat frame. An air cleaner is supported by the seat frame and rear frame. The air cleaner is located rearward of the engine. An ECU is located below the seat. The ECU is fixed to the seat frame via a stay. An ignition coil is located forward of the engine. The ignition coil supplies electric power to a spark plug attached to the engine.
According to JP 2010-167796 A, an air cleaner and fuel tank are located above the engine. The air cleaner is located rearward of the head pipe and forward of the fuel tank. Since the air cleaner is located forward of the fuel tank, air can be easily taken in.
According to JP 2012-56441 A, the ECU is located rearward of the engine, and the ignition coil is located forward of the engine. In order to concentrate the mass of the vehicle and reduce the wiring, the ECU and ignition coil are preferably located near the engine.
However, the present inventors discovered that, if the air cleaner and fuel tank are located above the engine, as in JP 2010-167796 A, the mass of the vehicle cannot be concentrated if the ECU and ignition coil are positioned in certain ways.
For example, the ECU and ignition coil may be positioned between the engine and fuel tank as measured in a top-to-bottom direction to reduce the wiring. However, when the effects of heat from the engine on the ECU and ignition coil are considered, the ECU and ignition coil are preferably located distant from the engine. Thus, if the ECU and ignition coil are to be positioned between the engine and fuel tank as measured in a top-to-bottom direction, the fuel tank must be located distant from the engine. This makes it difficult to concentrate the mass of the vehicle as measured in a top-to-bottom direction of the vehicle. In addition, the wiring is increased.
Further, it is desirable to reduce the dimension of a motorcycle as measured in a top-to-bottom direction with respect to of the vehicle. Thus, if the ECU and ignition coil are positioned in the above-discussed manner, the fuel tank must extend rearward to ensure a certain capacity of the fuel tank while concentrating the mass of the vehicle as measured in a top-to-bottom direction with respect to the vehicle. This makes it difficult to concentrate the mass of the vehicle as measured in a front-to-rear direction with respect to the vehicle.
Furthermore, in a motorcycle, not only the fuel tank but also the air cleaner is required to have a certain capacity. Thus, the air cleaner and fuel tank are designed to be as large as possible without getting in the way of other vehicle components. As such, it is not always the case that the ECU and ignition coil can be located together anywhere close to the air cleaner or fuel tank.
Further, the air cleaner and fuel tank are required to have a certain capacity. In a motorcycle, where it is desirable to reduce the dimension as measured in a top-to-bottom direction with respect to the vehicle, the air cleaner and fuel tank must extend rearward if the ECU and ignition coil are to be positioned in the above-discussed manner, to concentrate the mass of the vehicle as measured in a top-to-bottom direction with respect to the vehicle while ensuring a certain capacity. This makes it difficult to concentrate the mass of the vehicle as measured in a front-to-rear direction with respect to the vehicle.